RFR: 8200607: Add missing include dependency in bitMap.hpp

[Per Liden]

bitMap.hpp uses the MEMFLAGS type, but doesn't include allocation.hpp, 
where that type is defined. This problem was exposed when writing a 
small gtest test-case, which only included bitMap.hpp.

Bug: https://bugs.openjdk.java.net/browse/JDK-8200607
Webrev: http://cr.openjdk.java.net/~pliden/8200607/webrev.0

/Per